Various mechanisms exist for resuming a machine from low power or off states. However, methods used by existing systems may be cumbersome and inefficient. Industry goals and standards for resume time are shrinking rapidly and the machines are slow to follow. Personal computers (PCs) are entering consumer electronics markets. As such, “instant on” and usability are imperative to maintain user pleasure.
Many newer systems will be configured with an extensible firmware interface (EFI) architecture. The pre-EFI Initialization (PEI) flow of an Intel® Platform Innovation Framework for the Extensible Firmware Interface, for instance, may be found on the public Internet at URL www-intel-com/technology/framework. The PEI flow is responsible for restoring the machine from an S3 low power state. The S3 power state is defined in the industry standard specification for Advanced Configuration and Power Interface (ACPI) which may be found on the public Internet at www-acpi-com. It should be noted that periods have been replaced with dashes in URLs within this document to avoid inadvertent hyperlinks.
Some existing system vendors work around issues of S3 resume time by writing monolithic and awkward code that restores some settings from CMOS. Other vendors are hindered by performing algorithmic calculations on the S3 path but are not achieving the requisite boot times.